import pygame

class Ship():
	def __init__(self, ai_settings, screen):
		"""初始化飞船并设置其初始位置"""
		self.screen = screen
		self.ai_settings = ai_settings
		
		# 加载飞船图像并获取外接矩形
		self.image = pygame.image.load('images/ship2.png')
		self.rect = self.image.get_rect()
		self.screen_rect = screen.get_rect()
		
		# 将每艘飞船放置在屏幕底部中央
		self.rect.centerx = self.screen_rect.centerx
		self.rect.bottom = self.screen_rect.bottom
		
		# 在飞船属性center中存储小数值
		self.center = float(self.rect.centerx)
		
		# 移动标志
		self.moving_right = False
		self.moving_left = False
		
	def blitme(self):
		"""在指定位置绘制飞船"""
		self.screen.blit(self.image, self.rect)
		
		
	def update(self):
		"""根据移动标志调整飞船的位置"""
		
		# 更新飞船的center值，而不是rect
		if self.moving_right and self.rect.right < self.screen_rect.right:
			# self.rect.centerx += self.ai_settings.ship_speed_factor
			self.center += self.ai_settings.ship_speed_factor
		if self.moving_left and self.rect.left > 0:
			# self.rect.centerx -= self.ai_settings.ship_speed_factor
			self.center -= self.ai_settings.ship_speed_factor
			
		# 根据self.center更新rect对象
		self.rect.centerx = self.center
			
			
	def center_ship(self):
		"""让飞船在屏幕上居中"""
		self.center = self.screen_rect.centerx
			
			
			
			
			
			
			
			
			
		
		
		
		
		
		
		
		